NAPA (KPIX) -- With climate change raising awareness about the need to keep carbon out of the atmosphere, one Napa Valley company is offering a way to dispose of agricultural waste while keeping it out of the air.
Neatly pruned grapevines line Silverado Trail in Napa County. But most of the clippings end up in large burning piles that sends plumes of smoke across the valley.
While that has been a common method to dispose of clippings for generations, at Piña Vineyard Management, co-owner Davie Piña is betting that things are going to change.
"We think they're going to stop open burning because of the smoke issue and because of all the other hazardous parts to this," he said.
Pina's company has developed a portable incinerator called an air-curtain burner that can be brought into the fields. Waste wood is dumped into the burning chamber, but a powerful jet of air across the top keeps the smoke from escaping, reburning it so almost all material is vaporized.
"With this machine, it eliminates the vast majority of all those harmful smoke particles that get free, and all the other things it off-gasses," said Piña.
A few other Napa vineyards -- mostly organic growers -- are using the same technology. Pina's creation is a burner that can be used onsite, eliminating the expense of transporting the waste material.
His machine has another function as well. If the flaming wood is covered with a layer of dirt, it cuts off the oxygen. The organic material continues to burn, leaving nothing behind but carbon.
"It's just like charcoal," Piña said. "If you put heat and air to it, it burns up. But if you keep the air off of it -- you bake it -- you can maintain just the carbon left over."
That end-product is known as "biochar." What look like chunks of burned wood are actually feather-light masses of pure carbon. Piña said if you return the biochar to the soil, it will stay there, sequestered in the earth while providing one more amazing benefit.
"When you put it into the soil, those little carbon structures absorb moisture and they hold moisture and they slowly release it," said Pina. "So when you have a wet winter, it'll absorb that moisture. And then as the spring and fall go, it will release that moisture."
A method of disposing of agricultural waste that sequesters carbon and preserves water? It sounds like an idea that's time has come. Piña thinks so and believes it's just a matter of time before his neighbors will too.
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